Selectively assemblable absorption cell



July 28, 1970 P. A. WILKS, JR

SELECTIVELY ASSEMBLABLE ABSORPTION CELL Filed 00 2'7, 196'? FIG.4

N sfisluis 271274.211

lflvgmon fa/Z A. Wil/ts Jr:

fuyflb 2 M ATTCRNEYS United States Patent Oflice 3,521,964 SELECTIVELY ASSEMBLABLE ABSORPTION CELL Paul A. WiIks, Jr., Darien, Conn., assignor to Willis Scientific Corporation, South Norwalk, Conn., a corporation of Connecticut Filed Oct. 27, 1967, Ser. No. 678,669 Int. Cl. G01n 1/10, 21/00 U.S. Cl. 356-246 3 Claims ABSTRACT OF THE DISCLOSURE A liquid sample holder for spectrophotometers wherein a pair of optically transparent windows, eachhaving a depresion in one face thereof, may be assembled in any one of several positions in a two-piece separable holding "unit to provide various pathlengths.

etersmay be used to analyze liquid,.gases or solid samples.

A wide iJariety of accessories must be employed for holding the different forms of sample. To properly equip such spectrofihotometers was expensive since a substantial supplement ary investment was usually necessary to'acquire new sample accessories to handle only the classical variety off iproblems. The liquid sample holders were rather inflexible since in order to obtain different pathlengths for the (samples, a number of different structures were usually employed. Such structures not only added to the total investment in spectrophotometers but were generally cumberspme and complicated in structure so that they could ndt be quickly and accurately handled in the laboratoryf.

One of the objects of the present invention is to provide an'limproved sample holder for spectrophoto'meters.

Another of the objects of the present invention is to providejq'a sample holder wherein the pathlength therethrough inaybe selectively varied.

In one aspect of the present invention the absorption cell or liquid sample holder may comprise a pair of optically transparent windows formed of a material .with each window having a circular depression in one face thereof and the other face fiat. Two-piece separable holding means are provided for holding each pair of windows in one of a number of different assembled relationships. The windows may be assembled with both depressions against each other, both depressions awayfrom each other or with a depression of one window against a flat surface of the other window. Thus, by selecting the assembly relationship with a pair of windows, different pathlengths through the assembled windows may be readily provided.

Other objects, advantages and features of the present invention will be apparent upon reference to the accompanying description when taken in conjunction with the following drawing, which is exemplary.

In the drawings: FIG. 1 is an overall perspective view of the hquid sample holder of the present invention in position on a spectrophotometer;

FIG. 2 is a vertical sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a vertical sectional view showing the windows being positioned with their depressions against each other;

FIG. 4 is a perspective view similar to that of FIG. 3

Patented July 28, 7.970

but showing the windows assembled in another position; and

FIG. 5 is an elevational view of the positioned holder of FIG. 1.

Proceeding next to the drawings wherein like reference symbols indicate the same parts throughout the various views a specific embodiment of the present invention will be described in detail.

The sample holder according to the present invention is indicated generally at 10 in FIG. 1 and is illustrated as being mounted directly in the spectrophotometer on a cell slide 11 mounted on a backing plate 12 and secured to the spectrophotometer by clamps indicated at 13.

The sample holder is in the form of an absorption cell and comprises a pair of optically transparent windows 14 and 15 shown in FIG. 3 with each window having a fiat or back surface 16 and a circular depression 17 in the other face thereof. The depression, for example, may have a depth of 0.025 mm. The windows are formed of an optically transparent material which may be of a suitable material, for example, silver chloride. The windows are assembled in a holding structure comprising a holding piece 18 and a locking or retaining piece 19. The holding piece 18 is substantially cylindrical in form and has an internal flange 20 at one end thereof to define an annular seat 21; The other end of the holding piece 18 is provided with internal threads 22. The windows are positioned against a rubber O-ring 23 which is mounted against the seat 21- and then held in position by the locking piece 19 having threads 24 which are engageable with the threads of the holding piece 18.

The holder pieces 18 and 19, as an example, may be made of a plastic material Delrin, a trademark of Du Pont for a polyformaldehyde. When the two windows are positioned into the holder piece as shown in FIG. 2, the locking piece is then screwed in to form a seal. The characteristic of silver chloride of the windows is such as to insure sealing under these conditions. The assembled holder can be used without a beam condenser.

When the windows are assembled in the front-to-front position as shown in FIG. 3, the two depressions are against each other and the pathlength through the assem bled windows will be twice the depth of a depression.

In FIG. 4 a depression of window 14 is positioned against the rear or back face of window 15 and the sample would be enclosed therebetween whereby a path length equal to the depth of the depression is provided.

The windows of the present invention may also be placed back-to-back, that is, both depressions away from each other, and the two rear faces in contact so that the windows are assembled as two flats. These assembled positions as described above thus provide three pathlength variations attained merely by positioning of the windows with respect to each other and then assembling the windows in the separable two-piece holder.

Thus it can be seen that the present invention has provided a simple and low cost spectrophotometer accessory in the form of a sample holder. The holder has a variety of pathlengths which may be achieved merely by disassembling the two-piece holder and repositioning of the windows therein. The disclosed accessory adds suitably to the flexibility and adaptability of a spectrophotom= eter without incurring substantial additional investments.

It will be understood that various details of construe tions and arrangements of parts can be changed without departing from the spirit of the invention, except as d fined in the appended claims.

What is claimed is:

1. In a sample holder for spectrophotometers, a plastic absorption cell comprising two threadedly connected tubular parts, one of said parts having an internal annular flange at one end thereof to form a seat, and the other of said parts extending into said first part and terminating short of said flange, a pair of circular optically transparent window discs each having a first side and a second side, and said first sides having a circular depression in the face thereof, the depressions being similar, of equal depth and axially aligned, said windows being selectively arranged in fiat abutting relationship with the first side of one window abutting either the first side or the second side of the other window in said seat whereby liquid samples may be so contained in said depressions to pro vide varying desired pathlengths through said assembled windows.

2. A sample holder according to claim 1 wherein said seat is fiat and accommodates an O-ring therein for sealingly engaging said windows therein.

3. In a sample holder as claimed in claim 2 with each depression having a depth in the range of 0.025 mm. whereby pathlengths in the range of 0,050 mm, and 0.025 mm. are formed:

References Cited UNITED STATES PATENTS FOREIGN PATENTS 10/1956 Germany OTHER REFERENCES Fisher Sci. cat, 1963, pp. 700-701 RONALD L. WIBERT, Primary Examiner W. A. SKLAR, Assistant Examiner 

